Claire's dream may be a pre-cursor to later events. In the dream Locke implies that she should have raised Aaron and by giving him up, it directly led to "bad things" happening.

Claire's dream was a reference to in the future. John Locke, who was a good human (white), became eventually taken by The Man in Black (thus being a bad person and thus wearing black). And the Man in Black, eventually became her "friend". The plane in the dream is a reference to Claire's escape in the final episode (The End). Also the crib is a reference to her crib in Lighthouse (Substitute baby).